1. Field of the Invention
The present invention relates to magnetic disk drives, and more particularly, to binary codewords for identifying tracks on a rotating magnetic media in the disk drive.
2. Description of the Prior Art and Related Information
In order to remain competitive, disk drive manufacturers must continually provide increased data storage capacity while rigidly controlling disk drive manufacturing cost. Sampled data techniques such as partial response with maximum likelihood detection (PRML) are applied to data read from the magnetic disk to increase recording densities. Maximum likelihood detection is performed in real time using a Viterbi sequence detector. An error in the maximum likelihood detection generally causes multiple bit errors.
Existing track identification (TID) codewords may be based on a generalized Gray code that has a Hamming distance of three between adjacent TID codewords for correcting a single bit error. An example of TID codewords capable of correcting a single bit error is disclosed in U.S. Pat. No. 6,226,138 to Blaum et al. The Blaum et al patent recognizes that more than one bit error could be corrected if the Hamming distance between adjacent TID codewords could be increased. However, the Blaum et el. patent does not disclose or suggest a generalized Gray code capable of providing correction of more than a single bit error.
Accordingly, there exists a need for TID codewords that may allow correction of more than one bit error and that have the advantages of a generalized Gray code. The present invention satisfies these needs.